The present invention relates to an apparatus for measuring continuous flow rate of gravitationally falling powdery and/or granular material (hereinafter referred to simply as "powders") by sensing the moment exerted on deflector means impinged on by the falling powders.
A conventional apparatus of this type comprises a torsion wire suspending a rod, with deflector means secured to one end of the rod to be impinged on by the falling powders while the other end of the rod has a baffle plate immersed in a viscous fluid for damping the movement, and gives the flow rate by sensing the torsional stress in the wire. As a modification thereof, it is also conventional to replace the torsion wire with a rod, resiliently held for instance by a coil spring, to similarly give the flow rate by sensing the angular displacement of the rod.
In either of these conventional apparatuses, the deflector member is provided without any balancing or symmetry around the center of the torsional angularly displacing movement, and therefore the impingement of the powders on such deflector member causes not only the intended moment for rotation but also undesirable side effects in non-negligible, substantial degree, such for instance as lateral twisting of the torsion wire or frictional loss in the rod bearing portion. This will seriously affect the, precision of measurement particularly when the flow rate is quite small.